This invention relates to programmable logic array devices, and more particularly to techniques for programming such devices.
Illustrative programmable logic array devices requiring programming are shown in Cliff U.S. Pat. No. 5,237,219 and Cliff et al. U.S. Pat. No. 5,434,514. Typically, such devices are "programmed" in order to set them up to thereafter perform desired logic functions. In other words, the programming determines what logic functions the device will perform. The present invention is particularly of interest in connection with programming programmable logic array devices whose programming memory elements are volatile and reprogrammable. For example, such devices typically require reprogramming each time their power supplies are turned on (from having been off). Such devices may also require reprogramming whenever it is desired to change the logic functions they perform, which may occur during certain normal uses of the devices. Because such programming (or reprogramming) may have to be performed relatively frequently, and because the logic devices are generally not usable during programming, it is important to have rapid and efficient programming techniques.
Programmable logic array devices are often designed to be "general purpose" devices. In other words, the programmable logic device is made without any particular end use in mind. It is intended that the customer will use the number of such devices that is appropriate to the customer's application, and that the customer will program those devices in the manner required to enable them to pegform the logic required in the customer's application. Because the size and complexity of various customer applications may vary considerably, it would be desirable to have programming techniques that are modular and lend themselves to programming different numbers of devices with programs of different sizes.
In view of the foregoing, it is an object of this invention to provide improved techniques for programming programmable logic array devices.
It is another object of this invention to provide more rapid techniques for programming programmable logic array devices.
It is still another object of this invention to provide programmable logic array device programming techniques which lend themselves to programming any number of such devices with programs of any size or complexity.